// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file specifies a recursive data storage class called Value intended for
// storing settings and other persistable data.
//
// A Value represents something that can be stored in JSON or passed to/from
// JavaScript. As such, it is NOT a generalized variant type, since only the
// types supported by JavaScript/JSON are supported.
//
// IN PARTICULAR this means that there is no support for int64_t or unsigned
// numbers. Writing JSON with such types would violate the spec. If you need
// something like this, either use a double or make a string value containing
// the number you want.

#ifndef BASE_VALUES_H_
#define BASE_VALUES_H_

#include <stddef.h>
#include <stdint.h>

#include <iosfwd>
#include <map>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/base_export.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/strings/string16.h"
#include "base/strings/string_piece.h"

namespace base {

class BinaryValue;
class DictionaryValue;
class FundamentalValue;
class ListValue;
class StringValue;
class Value;

// The Value class is the base class for Values. A Value can be instantiated
// via the Create*Value() factory methods, or by directly creating instances of
// the subclasses.
//
// See the file-level comment above for more information.
class BASE_EXPORT Value {
public:
    enum class Type {
        NONE = 0,
        BOOLEAN,
        INTEGER,
        DOUBLE,
        STRING,
        BINARY,
        DICTIONARY,
        LIST,
        // Note: Do not add more types. See the file-level comment above for why.
    };

    enum TypeOld {
        TYPE_NULL = 0,
        TYPE_BOOLEAN,
        TYPE_INTEGER,
        TYPE_DOUBLE,
        TYPE_STRING,
        TYPE_BINARY,
        TYPE_DICTIONARY,
        TYPE_LIST
        // Note: Do not add more types. See the file-level comment above for why.
    };

    virtual ~Value();

    static std::unique_ptr<Value> CreateNullValue();

    // Returns the name for a given |type|.
    static const char* GetTypeName(Type type);

    // Returns the type of the value stored by the current Value object.
    // Each type will be implemented by only one subclass of Value, so it's
    // safe to use the Type to determine whether you can cast from
    // Value* to (Implementing Class)*.  Also, a Value object never changes
    // its type after construction.
    Type GetType() const { return type_; }

    // Returns true if the current object represents a given type.
    bool IsType(Type type) const { return type == type_; }

    // These methods allow the convenient retrieval of the contents of the Value.
    // If the current object can be converted into the given type, the value is
    // returned through the |out_value| parameter and true is returned;
    // otherwise, false is returned and |out_value| is unchanged.
    virtual bool GetAsBoolean(bool* out_value) const;
    virtual bool GetAsInteger(int* out_value) const;
    virtual bool GetAsDouble(double* out_value) const;
    virtual bool GetAsString(std::string* out_value) const;
    virtual bool GetAsString(string16* out_value) const;
    virtual bool GetAsString(const StringValue** out_value) const;
    virtual bool GetAsString(StringPiece* out_value) const;
    virtual bool GetAsBinary(const BinaryValue** out_value) const;
    // ListValue::From is the equivalent for std::unique_ptr conversions.
    virtual bool GetAsList(ListValue** out_value);
    virtual bool GetAsList(const ListValue** out_value) const;
    // DictionaryValue::From is the equivalent for std::unique_ptr conversions.
    virtual bool GetAsDictionary(DictionaryValue** out_value);
    virtual bool GetAsDictionary(const DictionaryValue** out_value) const;
    // Note: Do not add more types. See the file-level comment above for why.

    // This creates a deep copy of the entire Value tree, and returns a pointer
    // to the copy.  The caller gets ownership of the copy, of course.
    //
    // Subclasses return their own type directly in their overrides;
    // this works because C++ supports covariant return types.
    virtual Value* DeepCopy() const;
    // Preferred version of DeepCopy. TODO(estade): remove the above.
    std::unique_ptr<Value> CreateDeepCopy() const;

    // Compares if two Value objects have equal contents.
    virtual bool Equals(const Value* other) const;

    // Compares if two Value objects have equal contents. Can handle NULLs.
    // NULLs are considered equal but different from Value::CreateNullValue().
    static bool Equals(const Value* a, const Value* b);

protected:
    // These aren't safe for end-users, but they are useful for subclasses.
    explicit Value(Type type);
    Value(const Value& that);
    Value& operator=(const Value& that);

private:
    Type type_;
};

// FundamentalValue represents the simple fundamental types of values.
class BASE_EXPORT FundamentalValue : public Value {
public:
    explicit FundamentalValue(bool in_value);
    explicit FundamentalValue(int in_value);
    explicit FundamentalValue(double in_value);
    ~FundamentalValue() override;

    // Overridden from Value:
    bool GetAsBoolean(bool* out_value) const override;
    bool GetAsInteger(int* out_value) const override;
    // Values of both type Type::INTEGER and Type::DOUBLE can be obtained as
    // doubles.
    bool GetAsDouble(double* out_value) const override;
    FundamentalValue* DeepCopy() const override;
    bool Equals(const Value* other) const override;

private:
    union {
        bool boolean_value_;
        int integer_value_;
        double double_value_;
    };
};

class BASE_EXPORT StringValue : public Value {
public:
    // Initializes a StringValue with a UTF-8 narrow character string.
    explicit StringValue(StringPiece in_value);

    // Initializes a StringValue with a string16.
    explicit StringValue(const string16& in_value);

    ~StringValue() override;

    // Returns |value_| as a pointer or reference.
    std::string* GetString();
    const std::string& GetString() const;

    // Overridden from Value:
    bool GetAsString(std::string* out_value) const override;
    bool GetAsString(string16* out_value) const override;
    bool GetAsString(const StringValue** out_value) const override;
    bool GetAsString(StringPiece* out_value) const override;
    StringValue* DeepCopy() const override;
    bool Equals(const Value* other) const override;

private:
    std::string value_;
};

class BASE_EXPORT BinaryValue : public Value {
public:
    // Creates a BinaryValue with a null buffer and size of 0.
    BinaryValue();

    // Creates a BinaryValue, taking ownership of the bytes pointed to by
    // |buffer|.
    BinaryValue(std::unique_ptr<char[]> buffer, size_t size);

    ~BinaryValue() override;

    // For situations where you want to keep ownership of your buffer, this
    // factory method creates a new BinaryValue by copying the contents of the
    // buffer that's passed in.
    static std::unique_ptr<BinaryValue> CreateWithCopiedBuffer(const char* buffer,
        size_t size);

    size_t GetSize() const { return size_; }

    // May return NULL.
    char* GetBuffer() { return buffer_.get(); }
    const char* GetBuffer() const { return buffer_.get(); }

    // Overridden from Value:
    bool GetAsBinary(const BinaryValue** out_value) const override;
    BinaryValue* DeepCopy() const override;
    bool Equals(const Value* other) const override;

private:
    std::unique_ptr<char[]> buffer_;
    size_t size_;

    DISALLOW_COPY_AND_ASSIGN(BinaryValue);
};

// DictionaryValue provides a key-value dictionary with (optional) "path"
// parsing for recursive access; see the comment at the top of the file. Keys
// are |std::string|s and should be UTF-8 encoded.
class BASE_EXPORT DictionaryValue : public Value {
public:
    using Storage = std::map<std::string, std::unique_ptr<Value>>;
    // Returns |value| if it is a dictionary, nullptr otherwise.
    static std::unique_ptr<DictionaryValue> From(std::unique_ptr<Value> value);

    DictionaryValue();
    ~DictionaryValue() override;

    // Overridden from Value:
    bool GetAsDictionary(DictionaryValue** out_value) override;
    bool GetAsDictionary(const DictionaryValue** out_value) const override;

    // Returns true if the current dictionary has a value for the given key.
    bool HasKey(StringPiece key) const;

    // Returns the number of Values in this dictionary.
    size_t size() const { return dictionary_.size(); }

    // Returns whether the dictionary is empty.
    bool empty() const { return dictionary_.empty(); }

    // Clears any current contents of this dictionary.
    void Clear();

    // Sets the Value associated with the given path starting from this object.
    // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes
    // into the next DictionaryValue down.  Obviously, "." can't be used
    // within a key, but there are no other restrictions on keys.
    // If the key at any step of the way doesn't exist, or exists but isn't
    // a DictionaryValue, a new DictionaryValue will be created and attached
    // to the path in that location. |in_value| must be non-null.
    void Set(StringPiece path, std::unique_ptr<Value> in_value);
    // Deprecated version of the above. TODO(estade): remove.
    void Set(StringPiece path, Value* in_value);

    // Convenience forms of Set().  These methods will replace any existing
    // value at that path, even if it has a different type.
    void SetBoolean(StringPiece path, bool in_value);
    void SetInteger(StringPiece path, int in_value);
    void SetDouble(StringPiece path, double in_value);
    void SetString(StringPiece path, StringPiece in_value);
    void SetString(StringPiece path, const string16& in_value);

    // Like Set(), but without special treatment of '.'.  This allows e.g. URLs to
    // be used as paths.
    void SetWithoutPathExpansion(StringPiece key,
        std::unique_ptr<Value> in_value);
    // Deprecated version of the above. TODO(estade): remove.
    void SetWithoutPathExpansion(StringPiece key, Value* in_value);

    // Convenience forms of SetWithoutPathExpansion().
    void SetBooleanWithoutPathExpansion(StringPiece path, bool in_value);
    void SetIntegerWithoutPathExpansion(StringPiece path, int in_value);
    void SetDoubleWithoutPathExpansion(StringPiece path, double in_value);
    void SetStringWithoutPathExpansion(StringPiece path, StringPiece in_value);
    void SetStringWithoutPathExpansion(StringPiece path,
        const string16& in_value);

    // Gets the Value associated with the given path starting from this object.
    // A path has the form "<key>" or "<key>.<key>.[...]", where "." indexes
    // into the next DictionaryValue down.  If the path can be resolved
    // successfully, the value for the last key in the path will be returned
    // through the |out_value| parameter, and the function will return true.
    // Otherwise, it will return false and |out_value| will be untouched.
    // Note that the dictionary always owns the value that's returned.
    // |out_value| is optional and will only be set if non-NULL.
    bool Get(StringPiece path, const Value** out_value) const;
    bool Get(StringPiece path, Value** out_value);

    // These are convenience forms of Get().  The value will be retrieved
    // and the return value will be true if the path is valid and the value at
    // the end of the path can be returned in the form specified.
    // |out_value| is optional and will only be set if non-NULL.
    bool GetBoolean(StringPiece path, bool* out_value) const;
    bool GetInteger(StringPiece path, int* out_value) const;
    // Values of both type Type::INTEGER and Type::DOUBLE can be obtained as
    // doubles.
    bool GetDouble(StringPiece path, double* out_value) const;
    bool GetString(StringPiece path, std::string* out_value) const;
    bool GetString(StringPiece path, string16* out_value) const;
    bool GetStringASCII(StringPiece path, std::string* out_value) const;
    bool GetBinary(StringPiece path, const BinaryValue** out_value) const;
    bool GetBinary(StringPiece path, BinaryValue** out_value);
    bool GetDictionary(StringPiece path,
        const DictionaryValue** out_value) const;
    bool GetDictionary(StringPiece path, DictionaryValue** out_value);
    bool GetList(StringPiece path, const ListValue** out_value) const;
    bool GetList(StringPiece path, ListValue** out_value);

    // Like Get(), but without special treatment of '.'.  This allows e.g. URLs to
    // be used as paths.
    bool GetWithoutPathExpansion(StringPiece key, const Value** out_value) const;
    bool GetWithoutPathExpansion(StringPiece key, Value** out_value);
    bool GetBooleanWithoutPathExpansion(StringPiece key, bool* out_value) const;
    bool GetIntegerWithoutPathExpansion(StringPiece key, int* out_value) const;
    bool GetDoubleWithoutPathExpansion(StringPiece key, double* out_value) const;
    bool GetStringWithoutPathExpansion(StringPiece key,
        std::string* out_value) const;
    bool GetStringWithoutPathExpansion(StringPiece key,
        string16* out_value) const;
    bool GetDictionaryWithoutPathExpansion(
        StringPiece key,
        const DictionaryValue** out_value) const;
    bool GetDictionaryWithoutPathExpansion(StringPiece key,
        DictionaryValue** out_value);
    bool GetListWithoutPathExpansion(StringPiece key,
        const ListValue** out_value) const;
    bool GetListWithoutPathExpansion(StringPiece key, ListValue** out_value);

    // Removes the Value with the specified path from this dictionary (or one
    // of its child dictionaries, if the path is more than just a local key).
    // If |out_value| is non-NULL, the removed Value will be passed out via
    // |out_value|.  If |out_value| is NULL, the removed value will be deleted.
    // This method returns true if |path| is a valid path; otherwise it will
    // return false and the DictionaryValue object will be unchanged.
    bool Remove(StringPiece path, std::unique_ptr<Value>* out_value);

    // Like Remove(), but without special treatment of '.'.  This allows e.g. URLs
    // to be used as paths.
    virtual bool RemoveWithoutPathExpansion(StringPiece key,
        std::unique_ptr<Value>* out_value);

    // Removes a path, clearing out all dictionaries on |path| that remain empty
    // after removing the value at |path|.
    bool RemovePath(StringPiece path, std::unique_ptr<Value>* out_value);

    // Makes a copy of |this| but doesn't include empty dictionaries and lists in
    // the copy.  This never returns NULL, even if |this| itself is empty.
    std::unique_ptr<DictionaryValue> DeepCopyWithoutEmptyChildren() const;

    // Merge |dictionary| into this dictionary. This is done recursively, i.e. any
    // sub-dictionaries will be merged as well. In case of key collisions, the
    // passed in dictionary takes precedence and data already present will be
    // replaced. Values within |dictionary| are deep-copied, so |dictionary| may
    // be freed any time after this call.
    void MergeDictionary(const DictionaryValue* dictionary);

    // Swaps contents with the |other| dictionary.
    virtual void Swap(DictionaryValue* other);

    // This class provides an iterator over both keys and values in the
    // dictionary.  It can't be used to modify the dictionary.
    class BASE_EXPORT Iterator {
    public:
        explicit Iterator(const DictionaryValue& target);
        Iterator(const Iterator& other);
        ~Iterator();

        bool IsAtEnd() const { return it_ == target_.dictionary_.end(); }
        void Advance() { ++it_; }

        const std::string& key() const { return it_->first; }
        const Value& value() const { return *it_->second; }

    private:
        const DictionaryValue& target_;
        Storage::const_iterator it_;
    };

    // Overridden from Value:
    DictionaryValue* DeepCopy() const override;
    // Preferred version of DeepCopy. TODO(estade): remove the above.
    std::unique_ptr<DictionaryValue> CreateDeepCopy() const;
    bool Equals(const Value* other) const override;

private:
    Storage dictionary_;

    DISALLOW_COPY_AND_ASSIGN(DictionaryValue);
};

// This type of Value represents a list of other Value values.
class BASE_EXPORT ListValue : public Value {
public:
    using Storage = std::vector<std::unique_ptr<Value>>;
    using const_iterator = Storage::const_iterator;
    using iterator = Storage::iterator;

    // Returns |value| if it is a list, nullptr otherwise.
    static std::unique_ptr<ListValue> From(std::unique_ptr<Value> value);

    ListValue();
    ~ListValue() override;

    // Clears the contents of this ListValue
    void Clear();

    // Returns the number of Values in this list.
    size_t GetSize() const { return list_.size(); }

    // Returns whether the list is empty.
    bool empty() const { return list_.empty(); }

    // Sets the list item at the given index to be the Value specified by
    // the value given.  If the index beyond the current end of the list, null
    // Values will be used to pad out the list.
    // Returns true if successful, or false if the index was negative or
    // the value is a null pointer.
    bool Set(size_t index, Value* in_value);
    // Preferred version of the above. TODO(estade): remove the above.
    bool Set(size_t index, std::unique_ptr<Value> in_value);

    // Gets the Value at the given index.  Modifies |out_value| (and returns true)
    // only if the index falls within the current list range.
    // Note that the list always owns the Value passed out via |out_value|.
    // |out_value| is optional and will only be set if non-NULL.
    bool Get(size_t index, const Value** out_value) const;
    bool Get(size_t index, Value** out_value);

    // Convenience forms of Get().  Modifies |out_value| (and returns true)
    // only if the index is valid and the Value at that index can be returned
    // in the specified form.
    // |out_value| is optional and will only be set if non-NULL.
    bool GetBoolean(size_t index, bool* out_value) const;
    bool GetInteger(size_t index, int* out_value) const;
    // Values of both type Type::INTEGER and Type::DOUBLE can be obtained as
    // doubles.
    bool GetDouble(size_t index, double* out_value) const;
    bool GetString(size_t index, std::string* out_value) const;
    bool GetString(size_t index, string16* out_value) const;
    bool GetBinary(size_t index, const BinaryValue** out_value) const;
    bool GetBinary(size_t index, BinaryValue** out_value);
    bool GetDictionary(size_t index, const DictionaryValue** out_value) const;
    bool GetDictionary(size_t index, DictionaryValue** out_value);
    bool GetList(size_t index, const ListValue** out_value) const;
    bool GetList(size_t index, ListValue** out_value);

    // Removes the Value with the specified index from this list.
    // If |out_value| is non-NULL, the removed Value AND ITS OWNERSHIP will be
    // passed out via |out_value|.  If |out_value| is NULL, the removed value will
    // be deleted.  This method returns true if |index| is valid; otherwise
    // it will return false and the ListValue object will be unchanged.
    virtual bool Remove(size_t index, std::unique_ptr<Value>* out_value);

    // Removes the first instance of |value| found in the list, if any, and
    // deletes it. |index| is the location where |value| was found. Returns false
    // if not found.
    bool Remove(const Value& value, size_t* index);

    // Removes the element at |iter|. If |out_value| is NULL, the value will be
    // deleted, otherwise ownership of the value is passed back to the caller.
    // Returns an iterator pointing to the location of the element that
    // followed the erased element.
    iterator Erase(iterator iter, std::unique_ptr<Value>* out_value);

    // Appends a Value to the end of the list.
    void Append(std::unique_ptr<Value> in_value);
#if !defined(OS_LINUX)
    // Deprecated version of the above. TODO(estade): remove.
    void Append(Value* in_value);
#endif

    // Convenience forms of Append.
    void AppendBoolean(bool in_value);
    void AppendInteger(int in_value);
    void AppendDouble(double in_value);
    void AppendString(StringPiece in_value);
    void AppendString(const string16& in_value);
    void AppendStrings(const std::vector<std::string>& in_values);
    void AppendStrings(const std::vector<string16>& in_values);

    // Appends a Value if it's not already present. Returns true if successful,
    // or false if the value was already
    bool AppendIfNotPresent(std::unique_ptr<Value> in_value);

    // Insert a Value at index.
    // Returns true if successful, or false if the index was out of range.
    bool Insert(size_t index, std::unique_ptr<Value> in_value);

    // Searches for the first instance of |value| in the list using the Equals
    // method of the Value type.
    // Returns a const_iterator to the found item or to end() if none exists.
    const_iterator Find(const Value& value) const;

    // Swaps contents with the |other| list.
    virtual void Swap(ListValue* other);

    // Iteration.
    iterator begin() { return list_.begin(); }
    iterator end() { return list_.end(); }

    const_iterator begin() const { return list_.begin(); }
    const_iterator end() const { return list_.end(); }

    // Overridden from Value:
    bool GetAsList(ListValue** out_value) override;
    bool GetAsList(const ListValue** out_value) const override;
    ListValue* DeepCopy() const override;
    bool Equals(const Value* other) const override;

    // Preferred version of DeepCopy. TODO(estade): remove DeepCopy.
    std::unique_ptr<ListValue> CreateDeepCopy() const;

private:
    Storage list_;

    DISALLOW_COPY_AND_ASSIGN(ListValue);
};

// This interface is implemented by classes that know how to serialize
// Value objects.
class BASE_EXPORT ValueSerializer {
public:
    virtual ~ValueSerializer();

    virtual bool Serialize(const Value& root) = 0;
};

// This interface is implemented by classes that know how to deserialize Value
// objects.
class BASE_EXPORT ValueDeserializer {
public:
    virtual ~ValueDeserializer();

    // This method deserializes the subclass-specific format into a Value object.
    // If the return value is non-NULL, the caller takes ownership of returned
    // Value. If the return value is NULL, and if error_code is non-NULL,
    // error_code will be set with the underlying error.
    // If |error_message| is non-null, it will be filled in with a formatted
    // error message including the location of the error if appropriate.
    virtual std::unique_ptr<Value> Deserialize(int* error_code,
        std::string* error_str)
        = 0;
};

// Stream operator so Values can be used in assertion statements.  In order that
// gtest uses this operator to print readable output on test failures, we must
// override each specific type. Otherwise, the default template implementation
// is preferred over an upcast.
BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value);

BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
    const FundamentalValue& value)
{
    return out << static_cast<const Value&>(value);
}

BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
    const StringValue& value)
{
    return out << static_cast<const Value&>(value);
}

BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
    const DictionaryValue& value)
{
    return out << static_cast<const Value&>(value);
}

BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
    const ListValue& value)
{
    return out << static_cast<const Value&>(value);
}

// Stream operator so that enum class Types can be used in log statements.
BASE_EXPORT std::ostream& operator<<(std::ostream& out,
    const Value::Type& type);

} // namespace base

#endif // BASE_VALUES_H_
